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| Japanese Explosive Ordnance – Army Ammunition – Navy Ammunition |
| Chapter 4 – Section 1 |
| ARMY PROJECTILES |
| 40-mm Ho 301 High-Explosive Projectile |
| Projectile Dimensions: |
| Lenght of projectile (fuzed): 129 mm (5 3/32 inches). |
| Length of projectile (without fuze): 108 mm (4 1/4 inches). |
| Distance base to rotating band (lower edge): 15 mm (19/32 inch). |
| Width of rotating band: 8 mm (5/16 inch). |
| Diameter of rotating band: 41 mm (1 5/8 inches). |
| Diameter of body: 39 mm (1 17/32 inches). |
| Diameter of bourrelet: 39.5 mm (1 9/16 inches). |
| Width of bourrelet: 6 mm (1/4 inch). |
| Distance base to bourrelet (lower edge): 91 mm (3 19/32 inches). |
| Wall thickness (propellant chamber): 5 mm (13/64 inch). |
| Wall thickness (H.E. chamber): 4 mm (9/64 inch). |
| Weights: |
| Complete round fuzed: 1 pound, 4.7 ounces. |
| H.E. charge: 2 ounces. |
| Propellant: 0.4 ounce (10 grams). |
| Primer: 0.1 ounce. |
| Fuze, with gaine: 2.1 ounces. |
| Gaine: 0.2 ounce. |
| Primer Dimensions: |
| Length: 9 mm (11/32 inch). |
| Diameter (threads): 12 mm (16/32 inch). |
| T.P.I.: 34 L.H. |
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Weapon in which used: (Ho 301 40-mm aircraft cannon): This is an unusual weapon si-milar in design to an Oerlikon blow-back operated cannon, but with the head of the bolt machined as a piston which closes the breech at the forward end of its stroke. |
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Filling: The filling consists of TNT with a forward pellet of picric acid or TNT. |
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Propellant: The propellant consists of small, greenish-gray, square flakes of smokeless powder (approximately 1 mm square) enclosed in a silk bag which is inserted in the after cavity of the projectile. A sealing cup of thin aluminum fits around the after end of the propellant bag and the charge and cup are held in by a perforated base plate which screws (L.H.) into the base of the cavity. The base plate has an outer ring ot twelve 3/16-inch holes and a central hole threaded (L.H.) to receive the small flush primer. The aluminum sealing cup is pervorated by a single hole in the center to permit the flash from the primer to reach the propellant. The force of the propellant gases blows through the aluminum cup to open the main series of holes. |
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Fuze: This is a simple direct-acting nose fuze with a central axial striker held in the un-armed condition by a slotted safety block which in turn is held by two spring-loaded de-tents. |
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Remarks: There is also a practice projectile which has the same dimensions and appear-ance as the H.E. projectile. It is painted black over all and has a nose plug instead of a fuze. |
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Figure 229 – 40-mm Ho-301 High-Explosive Projectile. |
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